Bioabsorbable medical device with coating

ABSTRACT

A biodegradable, bioabsorbable medical device with a coating for capturing progenitor endothelial cells in vivo and delivering a therapeutic agent at the site of implantation. The coating on the medical device is provided with a bioabsorbable polymer composition such as a bioabsorbable polymer, copolymer, or terpolymer, and a copolymer or terpolymer additive for controlling the rate of delivery of the therapeutic agent.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.13/098,850, filed May 2, 2011, which is a continuation of U.S. patentapplication Ser. No. 11/875,887, filed on Oct. 20, 2007, now U.S. Pat.No. 7,959,942, which claims benefit of U.S. Provisional PatentApplication No. 60/862,409, filed Oct. 20, 2006. The disclosures of allthese applications are herein incorporated by reference in theirentirety.

All references cited in this specification, and their references, areincorporated by reference herein in their entirety where appropriate forteachings of additional or alternative details, features, and/ortechnical background.

The invention relates in embodiments disclosed herein to a novel medicaldevice with a coating. Such device may be configured for implantationinto vessels or luminal structures within the body. More particularly,the present invention in embodiments relates to stents and syntheticgrafts which are coated with a controlled-release matrix comprising amedicinal substance for direct delivery to the surrounding tissues, anda ligand attached thereto for capturing progenitor endothelial cellsthat may be found in the bodily fluids contacting the matrix (e.g.,blood-contacting surface). The captured cells may result in theformation of mature endothelium at site of injury. In particular, apolymer matrix/drug/ligand-coated stent may be used, for example, intherapy of diseases such as restenosis, artherosclerosis, andendoluminal reconstructive therapies.

A medical device of embodiments of the present invention may comprise apolymer composition comprising a base material formed from, orincluding, a bioabsorbable polymer, copolymer, or terpolymer. The basematerial may further comprise a copolymer or terpolymer additive. Oneadvantageous base material allows for a “soft” breakdown mechanismallowing for the breakdown of the component polymers to be lessinjurious to the surrounding tissue.

A persistent problem associated with the use of metallic devices such asstents in treating cardiovascular disease is the formation of scartissue coating of the stent at the site of implantation the so-calledprocess of restenosis. Moreover, metallic or polymeric non-absorbablestents may prevent vascular lumen remodeling and expansion. Numerousapproaches have been tried to prevent scar tissue, and reduce complementactivation of the immune response, which may be attendant to suchimplanted devices. Furthermore, an advantageous implant with a reducedinflammatory response and lower potential for trauma upon break-up of animplant and/or its component materials may be desired. A desirableimprovement target may be found in the need for increased flexibility ofshane and structure of medical devices for implantation, particularlyinto blood vessels.

Reference is made to U.S. Pat. No. 6,607,548 B2 (Inion), issued Aug. 19,2003, which discloses compositions that are biocompatible andbioresorbable using a lactic acid or glycolic acid based polymer orcopolymer blended with one or more copolymer additives. As a result,implants made from these blends are said to be cold-bendable withoutcrazing or cracking EP 0401844 discloses a blend of Poly-L-lactide withPoly D-DL-lactide.

It may be argued that bioabsorbable medical devices (such as stents) maybe more suitable in the treatment of vascular disease thannon-bioabsorbable medical devices. For example, it is known thatnon-biodegradable metallic stents can induce thrombosis by irritation ofthe blood vessel after since they are permanently embedded in the bloodvessel. Further, their mechanical properties may deteriorate impairingblood vessel properties.

Coated medical devices are available commercially and approved by theFDA. For example, drug eluting stents containing anti-cancer drugs suchas rapamycin and paclitaxel are commonly implanted into coronaryarteries and have become the preferred method for used in percutaneouscoronary interventions, because of their significant ability to reducerestenosis rates. One limitation of drug eluting stents has been thatthe patient needs to take supplemental oral drugs, such as aspirin andclopidrogel to prevent thrombosis from occurring at an early stage afterimplantation. Furthermore, the polymers used as a vehicle for drugdelivery in some devices may induce vessel irritation, endothelial celldysfunction, vessel hypersensitivity and chronic inflammation at thesite of stent implantation (Waksman 2006).

The present inventors have recognized that it may be advantageous todevelop a compatible polymer blends for medical devices, such as stentsand vascular synthetic grafts, which provide a toughening mechanism tothe base polymer when deployed into the body. In one embodiment, thebase polymer composition may be used to impart additional molecular freevolume to the base polymer to affect molecular motion sufficiently toallow for re-crystallization to occur at physiological conditions, forexample, upon the addition of molecular strain in deployment. They havefurther recognized that increased molecular free volume can alsoincrease the rate of water uptake adding both a plasticizing effect aswell as increasing the bulk degradation kinetics. The composition may beformulated to allow for a “soft” breakdown mechanism such that thebreakdown proceeds while being friendly to the surrounding tissue (lessinflammatory response, and rendering lower potential for trauma uponbreak up of an implant). By selecting a polymer or copolymer for eitherthe base or the additive or both, an enhanced hydrophilic property ofthe polymer blend may reduce complement activation and minimize orprevent opsonization. (see Dong and Feng, J of Biomedical MaterialsResearch part A DOI 10.1002, 2006).

SUMMARY

Disclosed in embodiments herein are biodegradable, bioabsorbable medicaldevices with a coating for the treatment or amelioration of variousdiseases, including vascular disease, and conditions in particular,artherosclerosis and/or restenosis.

In one embodiment, the medical device comprises a device forimplantation into a patient for the treatment of disease. The medicaldevice comprises a bioabsorbable, biodegradable material, which may be apolymer of synthetic or natural origin, which has the ability to undergodeformation when employed in vivo, for example, from a solid or rigidstate during manufacture to a flexible and pliable material afterimplantation in vivo, yet in its pliable form is capable of maintainingthe desired blood vessel diameter upon deployment in situ.

In one embodiment, the medical device comprises a polymer compositionand/or formulation, comprising: a polymer such as a poly(L-lactide), ora poly(D-lactide) as the base polymer, or copolymers thereof and whereinmodifying copolymers including, poly L (orD)-lactide-co-Tri-methylene-carbonate and poly L (orD)-lactide-co-.epsilon.-caprolactone can be used to link the basepolymers. These copolymers can be synthesized as block copolymers or as“blocky” random copolymers wherein the lactide chain length issufficiently long enough to crystallize. Such polymer compositions mayallow the development of a crystal morphology that can enhance themechanical properties of the medical device; enhance processingconditions, and provide potential of cross moiety crystallization, forexample, thermal cross-links. In this embodiment, the polymercomposition allows the development of the lactide racemate crystalstructure, between the L and D moieties, to further enhance themechanical properties of the medical device.

In another embodiment, the medical device may comprise a polymercomposition wherein the properties of the polymer composition can beengineered to produce a desired degradation time of the base polymer sothat the degradation time can be predicted after implantation of thedevice. For example, the medical device can comprise base polymershaving enhanced degradation kinetics. In this manner, the degradationtime of the base polymer can be shortened. For example, the startingmaterial used as base polymer can be a lower molecular weightcomposition and/or a base polymer that is more hydrophilic or liable tohydrolytic chain scission.

In another embodiment, medical device can comprise a polymer compositionwhich comprises a base copolymer wherein one polymer moiety issufficiently long enough and not sterically hindered to crystallize,such as L-lactide or D-lactide with a lesser or shorter polymer moiety,for example Glycolide or Polyethylene Glycol (PEG), ormonomethoxy-terminated PEG (PEG-MNE).

In another embodiment, compositions in addition to the base polymer, themodifying polymer or co-polymer may also have enhanced degradationkinetics such as with an e-caprolactone copolymer moiety wherein thecaprolactone remains amorphous with resulting segments more susceptibleto hydrolysis.

In another embodiment, the composition can incorporate PEG copolymers,for example either AB diblock or ABA triblock with the PEG moiety beingapproximately 1%. In this embodiment, the mechanical properties of theLactide (see Enderlie and Buchholz SFB May 2006) are maintained. In thisembodiment the incorporation of either PEG or PEG-MME copolymers mayalso be used to facilitate drug attachment to the polymer, for examplein conjunction with a drug eluding medical device.

In one embodiment, the polymer compositions are used to manufacturemedical device for implantation into a patient. The medical deviceswhich may have biodegradable, bioabsorbable properties as discussedabove, may include, but are not limited to stents, stent grafts,vascular synthetic grafts, catheters, vascular shunts, valves and thelike.

The coating on the medical device of embodiments of the presentinvention can comprise a bioabsorbable, biodegradable matrix comprisinga synthetic or naturally occurring polymer, or non-polymer material,which can be applied to the medical device, and can comprise similarbase polymers as the medical device. The coating on the medical devicecan further comprise a biological and/or pharmaceutical substance, forexample, drugs for delivery to the adjacent tissues where device isimplanted into the body. The coating may also include a radiopaquematerial to allow for easier identification of the medical device whenplaced in the body. Such drug or pharmaceutical substances orradioopaque materials may be bound to the matrix, for example, byreaction of such materials and substances with end groups of a polymercomprising the matrix, other chemical linkage (such as through linkersassociated with the polymer), by simple mixing (localized or dispersed)of the materials and substances into the matrix, and other methods knownin the art. Such coating may be applied to the medical device itself, ormay be applied to material or fabrication from which the medical deviceis made—for example applied to a tube structure from which a stent iscut (e.g. by laser cutting, photolasing, physical or air knife, etc.).

In another embodiment, the invention is directed to a method of coatinga medical device with the a bioabsorbable coating composition,comprising applying one or more layers of a matrix such as abiobsorbable polymer matrix to the medical device. Coatings at differentportions of the medical device may be the same or different. For examplein a stent, the coating located on the outer surface of the stent may bedifferent than the coating on the inner section of the stent. Further,the number of layers of coating on the outer surface of the stent mightbe different from the number of layers of coating on the inside of thestent. For example, the inner surface of a stent may have coating thatbreaks down slower than the coating on the outside of the stent, or haveadditional materials, or layers, associated therewith, for example aligand that captures cells, than the outer surface (which may forexample have drug eluting layer). Alternatively, or additionally, theinner layer may have a different drug or biological ligand associatedtherewith than the outer layer. Of course, the inner and outer coatingsmay be similar or identical to one another in terms ofpharmacological/biological effect.

In one embodiment, an implantable medical device is provided, comprisinga crystallizable polymer composition and a coating; said medical devicecomprising, a base polymer linked with a modifying copolymer in the formof block copolymer or blocky random copolymers, wherein the polymerchain length is sufficiently long enough to allow cross-moietycrystallization; and said coating comprising a bioabsorbable matrix anda ligand. In this embodiment, the ligand is configured to bind targetcells in vivo. The ligand can be a small molecule, a peptide, anantibody, antibody fragments, or combinations thereof and the targetcell is a progenitor endothelial cell antigen. In certain embodiments,the coating comprises one or more layers, and can comprise a matrixcomprising naturally occurring or synthetic biodegradable polymer. Inthis embodiment, matrix can comprise at least one of the groupconsisting of: tropoelastin, elastin, laminin, fibronectin, basementmembrane proteins, and cross-linked tropoelastin.

In one embodiment, the implantable medical device comprises a coatingwherein at least one coating layer, or the implantable medical deviceitself, comprises a radioopaque or radio-detectable material. Theradio-opaque material can be for example, tantalum, iodine, and thelike, which can be detected or imaged by X-ray techniques. In someembodiments, the implantable medical device can be impregnated with apharmacological or biological substance. In this embodiment, theradio-opaque material can be blended with the pharmaceutical substanceor a biological substance and the base polymers and or attached to thepolymer structure during manufacturing.

In alternate embodiments, the implantable medical device can comprise atube defining a lumen, said tube having an outer surface and an innersurface, said inner surface surrounding said lumen, wherein the outersurface can be coated with a composition comprising a pharmacologicalsubstance. In some embodiments, the outer or inner surface can be coatedwith a composition comprising a biological substance. In one embodiment,the pharmacological substance is at least one of the group consistingof: cyclosporin A, mycophenolic acid, mycophenolate mofetil acid,rapamycin, rapamycin derivatives, biolimus A9, CCI-779, RAD 001,AP23573, azathioprene, pimecrolimus, tacrolimus (FK506), tranilast,dexamethasone, corticosteroid, everolimus, retinoic acid, vitamin E,rosglitazone, simvastatins, fluvastatin, estrogen, 17.beta.-estradiol,hydrocortisone, acetaminophen, ibuprofen, naproxen, fluticasone,clobetasol, adalimumab, sulindac, dihydroepiandrosterone, testosterone,puerarin, platelet factor 4, basic fibroblast growth factor,fibronectin, butyric acid, butyric acid derivatives, paclitaxel,paclitaxel derivatives, LBM-642, deforolimus, and probucol.

In embodiments comprising a biological substance, the biologicalsubstance is at least one of the group consisting of:antibiotics/antimicrobials, antiproliferative agents, antineoplasticagents, antioxidants, endothelial cell growth factors, smooth musclecell growth and/or migration inhibitors, thrombin inhibitors,immunosuppressive agents, anti-platelet aggregation agents, collagensynthesis inhibitors, therapeutic antibodies, nitric oxide donors,antisense oligonucleotides, wound healing agents, therapeutic genetransfer constructs, peptides, proteins, extracellular matrixcomponents, vasodialators, thrombolytics, anti-metabolites, growthfactor agonists, antimitotics, steroids, steroidal antiinflammatoryagents, chemokines, proliferator-activated receptor-gamma agonists,proliferator-activated receptor-alpha agonists proliferator-activatedreceptor-beta agonists, proliferator-activated receptor-alpha/betaagonists, proliferator-activated receptor-delta agonists,NF.kappa.beta., proliferator-activated receptor-alpha-gamma agonists,nonsterodial antiinflammatory agents, angiotensin converting enzyme(ACE)inhibitors, free radical scavangers, inhibitors of the CX3CR1 receptorand anti-cancer chemotherapeutic agents.

In one embodiment, the implantable medical device can comprise acrystallizable bioabsorbable polymer composition comprises a basepolymer of from about 70% by weight of poly (L-lactide) with 30% byweight of modifying copolymer poly L-lactice-co-TMC.

In some embodiments, a bioabsorbable implant is provided comprising: acrystallizable composition comprising a base polymer of poly L-lactideor poly D-lactide linked with modifying copolymers comprising poly L (orD)-lactide-co-Tri-methylene-carbonate or poly L (orD)-lactide-co-.epsilon.-caprolactone in the form of block copolymers oras blocky random copolymers wherein the lactide chain length issufficiently long enough to allow cross-moiety crystallization; and aligand. In this embodiments, the bioabsorbable implant can have a basepolymer composition blend of 70% by weight of poly L-lactide with 30% byweight of modifying copolymer poly L-lactice-co-TMC.

In embodiments herein, the bioabsorbable implant comprises a ligandwhich can be a small molecule, a peptide, an antibody, antibodyfragments, or combinations thereof and the target cell is a progenitorendothelial cell. In this embodiment, the bioabsorbable an antibody orantibody fragments is specific for binding a progenitor endothelial cellmembrane antigen. The antibodies can bind to progenitor endothelial cellmembrane antigen and can be selected from the group consisting of CD34,CD45, CD133, CD14, CDw90, CD117, HLA-DR, VEGFR-1, VEGFR-2, CD146, CD130,CD131, stem cell antigen, stem cell factor 1, Tie-2, MCH-H-2Kk andMCH-HLA-DR.

In another embodiment, a bioabsorbable implant is provided, having atissue contacting surface and a fluid contacting surface, said implantcomprising a bioabsorbable, biocompatible first coating for controlledrelease of one or more pharmaceutical substances from said tissuecontacting surface, and a second coating comprising one or more ligandswhich bind to specific molecules on cell membranes of progenitorendothelial cells on the fluid contacting surface of the medical device.The bioabsorbable implant can be a stent, a vascular or other syntheticgraft, or a stent in combination with a synthetic graft. In someembodiments, the tissue contacting surface coating comprisespoly(DL-lactide-co-glycolide) and one or more pharmaceutical substances.In other embodiments the tissue contacting surface coating comprisespoly(DL-lactide), or poly(lactide-co-glycolide), and paclitaxel.

In one embodiment, the bioabsorbable implant comprises a pharmaceuticalsubstance is at least one of the group consisting ofantibiotics/antimicrobials, antiproliferative agents, antineoplasticagents, antioxidants, endothelial cell growth factors, smooth musclecell growth and/or migration inhibitors, thrombin inhibitors,immunosuppressive agents, anti-platelet aggregation agents, collagensynthesis inhibitors, therapeutic antibodies, nitric oxide donors,antisense oligonucleotides, wound healing agents, therapeutic genetransfer constructs, peptides, proteins, extracellular matrixcomponents, vasodialators, thrombolytics, anti-metabolites, growthfactor agonists, antimitotics, steroids, steroidal antiinflammatoryagents, chemokines, proliferator-activated receptor-gamma agonists,proliferator-activated receptor-alpha-gamma agonists,proliferator-activated receptor-alpha agonists, proliferator-activatedreceptor-beta agonists, proliferator-activated receptor-alpha/betaagonists, proliferator-activated receptor-delta agonists,NF.kappa.beta., nonsterodial antiinfammatory agents, angiotensinconverting enzyme(ACE) inhibitors, free radical scavangers, inhibitorsof the CX3CR1 receptor, and anti-cancer chemotherapeutic agents.

In other embodiments, the bioabsorbable implant comprises apharmaceutical substance selected from the group consisting ofcyclosporin A, mycophenolic acid, mycophenolate mofetil acid, rapamycin,rapamycin derivatives, biolimus A9, CCI-779, RAD 001, AP23573,azathioprene, pimecrolimus, tacrolimus (FK506), tranilast,dexamethasone, corticosteroid, everolimus, retinoic acid, vitamin E,rosglitazone, simvastatins, fluvastatin, estrogen, 17.beta.-estradiol,hydrocortisone, acetaminophen, ibuprofen, naproxen, fluticasone,clobetasol, adalimumab, sulindac, dihydroepiandrosterone, testosterone,puerarin, platelet factor 4, basic fibroblast growth factor,fibronectin, butyric acid, butyric acid derivatives, paclitaxel,paclitaxel derivatives, LBM-642, deforolimus, and probucol. In oneembodiment, the coating composition can comprise poly(DL-lactide)polymer comprises from about 50 to about 99% of the composition.

In one embodiment, the bioabsorbable implant comprising an outer coatingand an inner coating, either or both coatings comprise multiple layersof the poly(DL-lactide) polymer, poly(lactide-co-glycolide) copolymer,or mixture thereof and either or both coatings comprise multiple layersof the pharmaceutical substances.

The invention is also directed to methods of making the biodegradablepolymer compositions and methods for making the medical devices from thepolymer compositions disclosed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an embodiment which consists of a bioabsorbablemedical device with a coating.

FIG. 2 depicts representative data from experiments wherein the amountof anti-CD34 antibody was measured on bioabsorbable polymeric tubes.

FIG. 3 is a representative example of a fluorescent micrographs of DAPIstained Kg1a cells bound to bioabsorbable polymer tube with a coatingcomprising a matrix and anti-CD34 antibodies.

FIG. 4 is a representative example of a fluorescent micrographs of DAPIstained Kg1a cells bound to bioabsorbable polymer tube without a coatingor uncoated bioabsorbable polymer tube.

FIG. 5 is a representative example of a fluorescent micrographs of DAPIstained Kg1a cells bound to bioabsorbable polymer tube pre-treated withplasma deposition step.

FIG. 6 is a bar graph which illustrates the data from the various trialsfrom the cell the Kg1a binding experiments using coated and uncoatedbioabsorbable polymer tubes.

FIG. 7A is a representative example of a fluorescent micrographs of DAPIstained Kg1a cells bound to bioabsorbable polymer stent of theinvention. FIG. 7B is a representative example of a fluorescentmicrographs of DAPI stained Kg1a cells bound to a bioabsorbable polymerstent strut shown in FIG. 7A, seen here at a higher magnification.

FIG. 8 is an illustration of a tubular medical device depicting an innercoating and an outer coating surrounding the device structure. In thisembodiment, the device is depicted with multiple layers.

FIG. 9 is an illustration of a stent with a coating showing aperspective view of a stent strut with the layer in the outer surfaceand the inner, luminal surface with a coating.

DETAILED DESCRIPTION

In embodiments herein there is illustrated bioabsorbable polymericmedical devices having a coating comprising a bioabsorbable,biodegradable polymeric composition for delivering a therapeutic agent,and a ligand for capturing and binding progenitor endothelial cells.Such polymers and medical devices may be more biocompatible and lessimmunogenic than prior art polymeric medical devices.

In one embodiment, the medical device comprises a crimpable polymericstent, which can be inserted onto a balloon delivery system forimplantation into a tubular organ in the body, for example, into anartery, a duct or vein. Once deployed into an organ, the medical Aballoon expandable medical device may comprise a thermal balloon, ornon-thermal balloon, and the medical device can have a structure whichis crimpable during loading and expandable without stress crazing inphysiological conditions.

In another embodiment, the medical device comprises a structure whichcan orient and/or crystallize upon strain of deployment, for exampleduring balloon dilation, in order to improve its mechanical properties.

In another embodiment, the products resulting from breakdown of thepolymers comprising a medical device are “friendly” or less immunogenicto the host, for example to the vascular wall. In yet anotherembodiment, the medical device comprises polymers having slow breakdownkinetics which avoid tissue overload or other inflammatory responses atthe site of implantation. In one embodiment, a medical device may have aminimum of 30-day retention of clinically sufficient strength.

Medical devices of the invention, can be structurally configured toprovide the ability to change and conform to the area of implantation toallow for the normal reestablishment of local tissues. The medicaldevices can transition from solid to a “rubbery state” allowing foreasier surgical intervention, than, for example a stainless steel stent.

The polymer composition can comprise a base polymer which can be presentfrom about 60% to 95% by weight, or from about 70% to 80% by weight ofthe composition. In one embodiment, the polymer formulation can comprisefrom about 70% by weight poly (L-lactide) (about 1.5 to 3.5 IV or fromabout 2.5 to 3 IV) with the poly L-lactide-co-TMC (80/20 w/w) (1.0 to2.6 IV, or from about 1.4 to 1.6 IV).

In another embodiment, the polymer formulation comprises 70% by weighttriblock poly L-lactide-co-PEG(95/05 to 99/01, or from 89/2 to 99/01)(2,000 to 10,000 Mw PEG, or from about 6,000 to 8,000 Mw PEG) with thepoly L-lactide-co-TMC(70/30) (1.4 to 1.6 IV).

The polymer composition can also comprise a formulation of about 70% byweight diblock poly L-lactide-co-PEG-MME(95/05 to 99/01) (2,000 to10,000 Mw PEG-MME, or from about 6,000 to 10,000 Mw PEG-MME) with polyL-lactide-co-TMC(70/30 w/w) (1.4 to 1.6 IV).

In one embodiment, pharmaceutical or biological compositions can beincorporated with the polymers by for example grafting to the polymeractive sites, or coating. For example, the pharmaceutical or biologicalcompositions may be bound through the end groups of a polymer chainSimple admixing into the polymer or charge-charge interactions may alsobe employed to associate the pharmaceutical or biological compositionswith the polymers.

A medical device of the present invention can comprise any medicaldevice for implantation including stents, grafts, stent grafts,synthetic vascular grafts, shunts, catheters, and the like.

In embodiments disclosed herein, the medical device comprises a stent,which is structurally configured to be deployed into, for example, anartery or a vein, and be able to expand in situ, and conform to theblood vessel lumen to reestablish blood vessel continuity at the site ofinjury. The stent can be configured to have many different arrangements,and may comprise one or more of the polymeric compositions describedherein, so that it is crimpable when loading and expandable and flexibleat physiological conditions once deployed.

A biodegradable medical device of the present invention may comprise abase polymer comprising, for example poly L-Lactide or poly D-Lactide, amodifying co-polymer, such as poly L (or D)lactide-co-Tri-methylene-carbonate or poly L (orD)-lactide-co-e-caprolactone as described above.

Various embodiments of biodegradable polymeric stents, and/or stentwalls with different configuration are illustrated in FIGS. 1-42. Forexample, the stent is a tubular structure comprising struts operablydesigned to allow blood to traverse its walls so that the adjacenttissues are bathed or come in contact with it as blood flows through thearea. The particular stent design may depend on the size of the stentradially and longitudinally.

A method of the invention comprises a method for making a bioabsorbablepolymeric implant comprising:

blending a polymer composition comprising a crystallizable compositioncomprising a base polymer of poly L-lactide or poly D-lactide linkedwith modifying copolymers comprising poly L (orD)-lactide-co-Tri-methylene-carbonate or poly L (orD)-lactide-co-e-caprolactone in the form of block copolymers or asblocky random copolymers wherein the lactide chain length issufficiently long enough to allow cross-moiety crystallization;

molding said polymer composition to structurally configure said implant;and

cutting said implant to form desired patterns.

A method for fabricating the medical device comprises: preparing abiodegradable polymeric structure; designing said polymeric structure tobe configured to allow for implantation into a patient; cutting saidstructure into patterns configured to permit traversing of the devicethrough openings and to allow for crimping of the device. Of course, thepatterns and material comprising the device may be selected to allow forboth crimping and expansion.

In another embodiment of the invention, there is provided a medicaldevice for implanting into the lumen of a blood vessel or an organ witha lumen, which device provides a biocompatible system for the deliveryof therapeutic agents locally in a safe and controlled manner, andadditionally induces the formation of a functional endothelium at thesite of injury, which stimulates positive blood vessel remodeling.

One implantable medical device comprises a coating comprising abiocompatible matrix, which can be made of a composition for extended orcontrolled delivery of a pharmaceutical substance to adjacent tissue.The coating on the medical device further may comprise one or moreligands for capturing target cells on a surface of the medical device(for example, the luminal surface of a stent). Further, the coating mayinclude native/normal or genetically modified target cells which secretea desired pharmaceutical substance constitutively or when stimulated todo so. In one embodiment, circulating progenitor endothelial cells arethe target cells which can be captured and immobilized on the luminal orblood contacting surface of the device to restore, enhance or acceleratethe formation of a functional endothelium at the site of implantation ofthe device due to blood vessel injury.

In one embodiment, the medical device comprises, for example, a stent, asynthetic vascular graft or a catheter having a structure adapted forthe introduction into a patient. For example, in the embodiments whereinthe medical device is a stent or graft, the device is operablyconfigured to have a luminal or blood contacting surface and an outersurface which is adapted for contacting adjacent tissue when insertedinto a patient.

The medical device of the invention can be any device that isimplantable into a patient. For example, in one embodiment the device isfor insertion into the lumen of a blood vessels or a hollowed organ,such as stents, stent grafts, heart valves, catheters, vascularprosthetic filters, artificial heart, external and internal leftventricular assist devices (LVADs), and synthetic vascular grafts, forthe treatment of diseases such as cancer, vascular diseases, including,restenosis, artherosclerosis, thrombosis, blood vessel obstruction, orany other applications additionally covered by these devices.

The medical device of the invention can be any device used forimplanting into an organ or body part comprising a lumen, and can be,but is not limited to, a stent, a stent graft, a synthetic vasculargraft, a heart valve, a catheter, a vascular prosthetic filter, apacemaker, a pacemaker lead, a defibrillator, a patent foramen ovale(PFO) septal closure device, a vascular clip, a vascular aneurysmoccluder, a hemodialysis graft, a hemodialysis catheter, anatrioventricular shunt, an aortic aneurysm graft device or components, avenous valve, a sensor, a suture, a vascular anastomosis clip, anindwelling venous or arterial catheter, a vascular sheath and a drugdelivery port. The medical device can be made of numerous bioabsorbablematerials depending on the device, biodegradable materials such aspolylactide polymers and polyglycolide polymers or copolymers thereofare the most suitable.

In one embodiment, the medical device comprises a coating comprising amatrix which comprises a nontoxic, biocompatible, bioerodible andbiodegradable synthetic material. The coating may further comprise oneor more pharmaceutical substances or drug compositions for delivering tothe tissues adjacent to the site of implantation, and one or moreligands, such as a peptide, small and/or large molecules, and/orantibodies or combinations thereof for capturing and immobilizingprogenitor endothelial cells on the blood contacting surface of themedical device.

In one embodiment, the implantable medical device comprises a stent. Thestent can be selected from uncoated stents available in the art. Inaccordance with one embodiment, the stent is an expandable intraluminalendoprosthesis designed and configured to have a surface for attaching acoating for controlled or slow release of a therapeutic substance toadjacent tissues.

In one embodiment, the controlled-release matrix can comprise one ormore polymers and/or oligomers from various types and sources,including, natural or synthetic polymers, which are biocompatible,biodegradable, bioabsorbable and useful for controlled-released of themedicament. For example, in one embodiment, the naturally occurringpolymeric materials include proteins such as collagen, fibrin,tropoelastin, elastin, cross-linked tropoelastin and extracellularmatrix component, fibrin, fibronectin, laminin, derivatives thereof, orother biologic agents or mixtures thereof. In this embodiment of theinvention, the naturally-occurring material can be made by geneticengineering techniques from exogenous genes carried by vectors, such asa plasmid vector and engineered into a host, such as a bacterium. Inthis embodiment, desired polymer proteins such as tropoelastin andelastin can be produced and isolated for use in the matrix. In alternateembodiments, the naturally occurring polymeric matrices can be purifiedfrom natural sources by known methods or they can be obtained bychemical synthesis of the protein polymer. In certain embodiments, thenaturally occurring material can be chemically modified or synthesized,for example, by cross-linking the material such as proteins, or bymethylation, phosphorylation and the like. In another embodiment, thematrix can comprise a denuded blood vessel or blood vessel scaffoldsand/or components thereof.

In one embodiment, the matrix may comprise a synthetic material whichinclude polyesters such as polylactic acid, polyglycolic acid orcopolymers and or combinations thereof, a polyanhydride,polycaprolactone, polyhydroxybutyrate valerate, and other biodegradablepolymer, or mixtures or copolymers thereof. In this embodiment, thematrix may comprise poly(lactide-coglycolide) as the matrix polymer forcoating the medical device. For example, the poly(lactide-co-glycolide)composition may comprise at least one polymer of poly-DL-co-glycolide,poly(D,L-lactide-co-glycolide) or copolymer or mixtures thereof, and itmay be mixed together with the pharmaceutical substances to be deliveredto the tissues. The coating composition may be applied to the surface ofthe device using standard techniques such as spraying, dipping, and/orchemical vaporization. Alternatively, the poly(lactide-co-glycolide)(PGLA) solution can be applied as a single layer separating a layer orlayers of the pharmaceutical substance(s).

In another embodiment, the coating composition further comprisespharmaceutically acceptable polymers and/or pharmaceutically acceptablecarriers, for example, nonabsorbable polymers, such as ethylene vinylacetate (EVAC) and methylmethacrylate (MMA). The nonabsorbable polymer,for example, can aid in further controlling release of the substance byincreasing the molecular weight of the composition thereby delaying orslowing the rate of release of the pharmaceutical substance.

In certain embodiments, the polymer material or mixture of variouspolymers can be applied together as a composition with thepharmaceutical substance on the surface of the medical device and cancomprise a single layer. Multiple layers of composition can be appliedto form the coating. In another embodiment, multiple layers of polymermaterial or mixtures thereof can be applied between layers of thepharmaceutical substance. For example, the layers may be appliedsequentially, with the first layer directly in contact with the uncoatedsurface of the device and a second layer comprising the pharmaceuticalsubstance and having one surface in contact with the first layer and theopposite surface in contact with a third layer of polymer which is incontact with the surrounding tissue. Additional layers of the polymermaterial and drug composition can be added as required, alternating eachcomponent or mixtures of components thereof.

In another embodiment, the matrix may comprise non-polymeric materialssuch as nanoparticles formed of, for example, metallic alloys or othermaterials. In this embodiment, the coating on the medical device can beporous and the pharmaceutical substances can be trapped within andbetween the particles. In this embodiment, the size of the particles canbe varied to control the rate of release of the pharmaceutical substancetrapped in the particles depending on the need of the patient. In oneembodiment, the pharmaceutical composition can be aslow/controlled-release pharmaceutical composition.

Alternatively, the pharmaceutical substance can be applied as multiplelayers of a composition and each layer can comprise one or more drugssurrounded by polymer material. In this embodiment, the multiple layersof pharmaceutical substance can comprise a pharmaceutical compositioncomprising multiple layers of a single drug; one or more drugs in eachlayer, and/or differing drug compositions in alternating layers applied.In one embodiment, the layers comprising pharmaceutical substance can beseparated from one another by a layer of polymer material. In anotherembodiment, a layer of pharmaceutical composition may be provided to thedevice for immediate release of the pharmaceutical substance afterimplantation.

In one embodiment, the pharmaceutical substance or composition maycomprise one or more drugs or substances which can inhibit smooth musclecell migration and proliferation at the site of implantation, caninhibit thrombus formation, can promote endothelial cell growth anddifferentiation, and/or can inhibit restenosis after implantation of themedical device. Additionally, the capturing of the progenitorendothelial cells on the luminal surface of the medical device may beused to accelerate the formation of a functional endothelium at the siteof injury.

Examples of compounds or pharmaceutical compositions which can beincorporated in the matrix, include, but are not limited toprostacyclin, prostacyclin analogs, .alpha.-CGRP, .alpha.-CGRP analogsor .alpha.-CGRP receptor agonists; prazosin; monocyte chemoattactantprotein-1 (MCP-1); immunosuppressant drugs such as rapamycin, drugswhich inhibit smooth muscle cell migration and/or proliferation,antithrombotic drugs such as thrombin inhibitors, immunomodulators suchas platelet factor 4 and CXC-chemokine; inhibitors of the CX3 CR1receptor family; antiinflammatory drugs, steroids such asdihydroepiandrosterone (DHEA) testosterone, estrogens such as17.beta.-estradiol; statins such as simvastatin and fluvastatin;PPAR-alpha ligands such as fenofibrate and other lipid-lowering drugs,PPAR-delta and PPAR-gamma agonists such as rosiglitazone;PPAR-dual-.alpha.gamma. agonists, LBM-642, nuclear factors such asNF-.kappa.beta., collagen synthesis inhibitors, vasodilators such asacetylcholine, adenosine, 5-hydroxytryptamine or serotonin, substance P,adrenomedulin, growth factors which induce endothelial cell growth anddifferentiation such as basic fibroblast growth factor (bFGF),platelet-derived growth factor (PDGF), endothelial cell growth factor(EGF), vascular endothelial cell growth factor (VEGF); protein tyrosinekinase inhibitors such as Midostaurin and imatinib or anyanti-angionesis inhibitor compound; peptides or antibodies which inhibitmature leukocyte adhesion, antibiotics/antimicrobials, and othersubstances such as tachykinins, neurokinins or sialokinins, tachykininNK receptor agonists; PDGF receptor inhibitors such as MLN-518 andderivatives thereof, butyric acid and butyric acid derivatives puerarin,fibronectin, erythropoietin, darbepotin, serine proteinase-1 (SERP-1)and the like.

In particular embodiments of the invention, one or more of thepharmaceutical substances can be selected from everolimus, rapamycin,pimecrolimus, tacrolimus (FK506), biolimus A9, CCI-779, RAD 001,AP23573, dexamethasone, hydrocortisone, estradiol, acetaminophen,ibuprofen, naproxen, fluticasone, clobetasol, adalimumab, sulindac, andcombinations thereof. The aforementioned compounds and pharmaceuticalsubstances can be applied to the coating on the device alone or incombinations and/or mixtures thereof.

In one embodiment, the implantable medical device can comprise a coatingcomprising one or more barrier layers in between said one or more layersof matrix comprising said pharmaceutical substances. In this embodiment,the barrier layer may comprise a suitable biodegradable material,including but not limited to suitable biodegradable polymers including:polyesters such as PLA, PGA, PLGA, PPF, PCL, PCC, TMC and any copolymerof these; polycarboxylic acid, polyanhydrides including maleic anhydridepolymers; polyorthoesters; poly-amino acids; polyethylene oxide;polyphosphazenes; polylactic acid, polyglycolic acid and copolymers andmixtures thereof such as poly(L-lactic acid) (PLLA), poly(D,L-lactide),poly(lactic acid-co-glycolic acid), 50/50 (DL-lactide-co-glycolide);polydixanone; polypropylene fumarate; polydepsipeptides;polycaprolactone and co-polymers and mixtures thereof such aspoly(D,L-lactide-co-caprolactone) and polycaprolactone co-butylacrylate;polyhydroxybutyrate valerate and blends; polycarbonates such astyrosine-derived polycarbonates and arylates, polyiminocarbonates, andpolydimethyltrimethyl-carbonates; cyanoacrylate; calcium phosphates;polyglycosaminoglycans; macromolecules such as polysaccharides(including hyaluronic acid; cellulose, and hydroxypropylmethylcellulose; gelatin; starches; dextrans; alginates and derivativesthereof), proteins and polypeptides; and mixtures and copolymers of anyof the foregoing. The biodegradable polymer may also be a surfaceerodable polymer such as polyhydroxybutyrate and its copolymers,polycaprolactone, polyanhydrides (both crystalline and amorphous),maleic anhydride copolymers, and zinc-calcium phosphate. Of course, suchmaterials may in fabrication of the medical device be disposed in anappropriate solvent, such as water, ethanol, acetone etc. and mayinclude materials providing for radioopacity, such as diatrizoatesodium, tantalum etc. The number of barrier layers that the coating on adevice may have depends on the amount of therapeutic needed as dictatedby the therapy required by the patient. For example, the longer thetreatment, the more therapeutic substance required over a period oftime, the more barrier layers may be needed to provide thepharmaceutical substance in a timely and continued manner.

In one embodiment, the ligand is applied to the blood contacting surfaceof the medical device and the ligand specifically recognizes and binds adesired component or epitope on the surface of target cells in thecirculating blood. In one embodiment, the ligand is specificallydesigned to recognize and bind only the genetically-altered mammaliancell by recognizing only the genetically-engineered marker molecule onthe cell membrane of the genetically-altered cells. The binding of thetarget cells immobilizes the cells on the surface of the device.

In an alternate embodiment, the ligand on the surface of the medicaldevice for binding the genetically-altered cell is selected depending onthe genetically engineered cell membrane marker molecule. That is, theligand binds only to the cell membrane marker molecule or antigen whichis expressed by the cell from extrachromosomal genetic material providedto the cell so that only the genetically-modified cells can berecognized by the ligand on the surface of the medical device. In thismanner, only the genetically-modified cells can bind to the surface ofthe medical device. For example, if the mammalian cell is an endothelialcell, the ligand can be at least one type of antibody, antibodyfragments or combinations thereof the antibody may be specificallyraised against a specific target epitope or marker molecule on thesurface of the target cell. In this aspect of the invention, theantibody can be a monoclonal antibody, a polyclonal antibody, a chimericantibody, or a humanized antibody which recognizes and binds only to thegenetically-altered endothelial cell by interacting with the surfacemarker molecule and, thereby modulating the adherence of the cells ontothe surface of the medical device. The antibody or antibody fragment ofthe invention can be covalently or noncovalently attached to the surfaceof the matrix, or tethered covalently by a linker molecule to theoutermost layer of the matrix coating the medical device. In thisembodiment, for example, the monoclonal antibodies can further comprisesFab or F(ab′)2 fragments. The antibody fragment of the inventioncomprises any fragment size, such as large and small molecules whichretain the characteristic to recognize and bind the target antigen asthe antibody.

In another embodiment, the antibody or antibody fragment of theinvention recognize and bind antigens with specificity for the mammalbeing treated and their specificity is not dependent on cell lineage. Inone embodiment, for example, in treating restenosis wherein the cellsmay not be genetically modified to contain specific cell membrane markermolecules, the antibody or fragment is specific for selecting andbinding circulating progenitor endothelial cell surface antigen such asCD133, CD34, CD14, CDw90, CD117, HLA-DR, VEGFR-1, VEGFR-2, Muc-18(CD146), CD130, stem cell antigen (Sca-1), stem cell factor 1 (SCF/c-Kitligand), Tie-2, MHC such as H-2Kk and HLA-DR antigen.

In another embodiment, the coating of the medical device comprises atleast one layer of a biocompatible matrix as described above, the matrixcomprises an outer surface for attaching a therapeutically effectiveamount of at least one type of small molecule of natural or syntheticorigin. The small molecule recognizes and interacts with, for example,progenitor endothelial cells in the prevention, amelioration ortreatment of restenosis, to immobilize the cells on the surface of thedevice to form an endothelial layer. The small molecules can be used inconjunction with the medical device for the treatment of variousdiseases, and can be derived from a variety of sources such as cellularcomponents such as fatty acids, proteins, nucleic acids, saccharides andthe like, and can interact with an antigen on the surface of aprogenitor endothelial cell with the same results or effects as anantibody. In one aspect of this embodiment, the coating on the medicaldevice can further comprise a compound such as a growth factor asdescribed herewith in conjunction with the coating comprising anantibody or antibody fragment.

In another embodiment, the coating of the medical device comprises atleast one layer of a biocompatible matrix as described above, the matrixcomprising a luminal surface for attaching a therapeutically effectiveamount of at least one type of small molecule of natural or syntheticorigin. The small molecule recognizes and interacts with an antigen onthe target cell such as a progenitor endothelial cell surface toimmobilize the progenitor endothelial cell on the surface of the deviceto form endothelium. The small molecules can be derived from a varietyof sources such as cellular components including, fatty acids, peptides,proteins, nucleic acids, saccharides and the like and can interact, forexample, with a structure such as an antigen on the surface of aprogenitor endothelial cell with the same results or effects as anantibody.

In another embodiment, there is provided a method for treating,ameloriating, or preventing vascular disease such as restenosis andartherosclerosis, comprising administering a pharmaceutical substancelocally to a patient in need of such substance. The method comprisesimplanting into a vessel or hollowed organ of a patient a medical devicewith a coating, which coating comprises a pharmaceutical compositioncomprising a drug or substance for inhibiting smooth muscle cellmigration and thereby restenosis, and a biocompatible, biodegradable,bioerodible, nontoxic polymer or non-polymer matrix, wherein thepharmaceutical composition comprises a slow or controlled-releaseformulation for the delayed release of the drug. The coating on themedical device can also comprise a ligand such as an antibody forcapturing cells such as endothelial cells and or progenitor cells on theluminal surface of the device so that a functional endothelium isformed.

In another embodiment, there is provided a method of making a coatedmedical device or a medical device with a coating, which comprisesapplying to a surface of a medical device a polymer or non-polymermatrix and a pharmaceutical composition comprising one or more drugs,and applying a ligand to the medical device so that the ligand attachesto a surface of the device and is designed to bind molecules on the cellmembrane of circulating native or genetically engineered cells. In thisembodiment, the polymer matrix comprises a biocompatible, biodegradable,nontoxic polymer matrix such as collagen, tropocollagen, elastin,tropoelastin, cross-linked tropoelastin, poly(lactide-co-glycolide)copolymer, polysaccharides and one or more pharmaceutical substances,wherein the matrix and the substance(s) can be mixed prior to applyingto the medical device. In this embodiment, at least one type of ligandis applied to the surface of the device and can be added on top or onthe outer surface of the device with the drug/matrix composition incontact with the device surface. The method may alternatively comprisethe step of applying at least one layer of a pharmaceutical compositioncomprising one or more drugs and pharmaceutically acceptable carriers,and applying at least one layer of a polymer matrix to the medicaldevice.

In one embodiment, the matrix can be applied as one or more layers andwith or without the pharmaceutical substance, and the ligand can beapplied independently to the medical device by several methods usingstandard techniques, such as dipping, spraying or vapor deposition. Inan alternate embodiment, the polymer matrix can be applied to the devicewith or without the pharmaceutical substance. In this aspect of theinvention wherein a polymer matrix is applied without the drug, the drugcan be applied as a layer between layers of matrices. In otherembodiments, a barrier layer is applied between the layers comprisingthe pharmaceutical substances.

In one embodiment, the method comprises applying the pharmaceuticalcomposition as multiple layers with the ligand applied on the outermostsurface of the medical device so that the ligand such as antibodies canbe attached in the luminal surface of the device. In one embodiment, themethod for coating the medical device comprises: applying to a surfaceof said medical device at least one or more layers of a matrix, one ormore pharmaceutical substance(s), and a basement membrane component;applying to said at least one layer of said composition on said medicaldevice a solution comprising at least one type of ligand for binding andimmobilizing genetically-modified target cells; and drying said coatingon the medical device, such as a stent, under vacuum at lowtemperatures.

In another embodiment, the coating is comprised of a multiple componentpharmaceutical composition within the matrix such as containing a fastrelease pharmaceutical agent to retard early neointimalhyperplasia/smooth muscle cell migration and proliferation, and asecondary biostable matrix that releases a long acting agent formaintaining vessel patency or a positive blood vessel remodeling agent,such as endothelial nitric oxide synthase (eNOS), nitric oxide donorsand derivatives such as aspirin or derivatives thereof, nitric oxideproducing hydrogels, PPAR agonist such as PPAR-A ligands, tissueplasminogen activator, statins such as atorvastatin, erythropoietin,darbepotin, serine proteinase-1 (SERP-1) and pravastatin, steroids,and/or antibiotics.

In another embodiment, there is provided a therapeutic, drug deliverysystem and method for treating diseases in a patient. The therapeutic ordrug delivery system comprises a medical device with a coating composedof a matrix comprising at least one type of ligand for recognizing andbinding target cells such as progenitor endothelial cells orgenetically-altered mammalian cells and genetically-altered mammaliancells which have been at least singly or dually-transfected.

In one embodiment, the coating on the present medical device comprises abiocompatible matrix and at least one type of pharmaceutical substanceor ligand, which specifically recognizes and bind target cells such asprogenitor endothelial cells such as in the prevention or treatment ofrestenosis, or genetically-altered mammalian cells, onto the surface ofthe device, such as in the treatment of blood vessel remodeling andcancer.

Additionally, the coating of the medical device may optionally compriseat least an activating compound for regulating the expression andsecretion of the engineered genes of the genetically-altered cells.Examples of activator stimulatory compounds, include but is not limitedto chemical moieties, and peptides, such as growth factors. Inembodiments when the coating comprises at least one compound, thestimulus, activator molecule or compound may function to stimulate thecells to express and/or secrete at least one therapeutic substance forthe treatment of disease.

In one embodiment, the coating on the medical device comprises abiocompatible matrix which comprises an outer surface for attaching atherapeutically effective amount of at least one type of ligand such asan antibody, antibody fragment, or a combination of the antibody and theantibody fragment, or at least one type of molecule for binding theengineered marker on the surface of the genetically-modified cell. Theantibody or antibody fragment present recognizes and binds an antigen orthe specific genetically-engineered cell surface marker on the cellmembrane or surface of target cells so that the cells are immobilized onthe surface of the device. In one embodiment, the coating may optionallycomprise an effective amount of at least one compound for stimulatingthe immobilized progenitor endothelial cells to either accelerate theformation of a mature, functional endothelium if the target cells arecirculating progenitor cells, or to stimulate the bound cells to expressand secrete the desired gene products if the target aregenetically-altered cells on the surface of the medical device.

In one embodiment, the compound of the coating of the invention, forexample in treating restenosis, comprises any compound which stimulatesor accelerates the growth and differentiation of the progenitor cellinto mature, functional endothelial cells. In another embodiment, thecompound is for stimulating the genetically modified cells to expressand secrete the desired gene product. For example, a compound for use inthe invention may be a growth factor such as vascular endothelial growthfactor (VEGF), basic fibroblast growth factor, platelet-induced growthfactor, transforming growth factor beta 1, acidic fibroblast growthfactor, osteonectin, angiopoietin 1 (Ang-1), angiopoietin 2 (Ang-2),insulin-like growth factor, granulocyte-macrophage colony-stimulatingfactor, platelet-derived growth factor AA, platelet-derived growthfactor BB, platelet-derived growth factor AB and endothelial PAS protein1.

In another embodiment, for example when using genetically-alteredmammalian cells, the activating agents or compounds useful forstimulating the cells to express and secrete the genetically-engineeredgene products include, but are not limited to estrogen, tetracycline andother antibiotics, tamoxiphen, etc., and can be provided to the patientvia various routes of administration, such as through the skin via apatch and subcutaneously.

The invention also provides methods for treating, amelioriating, andpreventing a variety of diseases, such as vascular disease, cancer,blood vessel remodeling, severe coronary artery diseaseartherosclerosis, restenosis, thrombosis, aneurysm and blood vesselobstruction. In one embodiment, there is provided a method for retainingor sealing the medical device insert to the vessel wall, such as a stentor synthetic vascular graft, heart valve, abdominal aortic aneurysmdevices and components thereof, and for establishing vascularhomeostasis, thereby preventing excessive intimal hyperplasia as inrestenosis. In a method of treating atherosclerosis, the artery may beeither a coronary artery or a peripheral artery such as the femoralartery. Veins can also be treated using these techniques and medicaldevice.

With respect to the treatment, amelioration, and prevention ofrestenosis, the invention also provides an engineered method forinducing a healing response. In one embodiment, a method is provided forrapidly inducing the formation of a confluent layer of endothelium inthe luminal surface of an implanted device in a target lesion of animplanted vessel, in which the endothelial cells express nitric oxidesynthase and other anti-inflammatory and inflammation-modulatingfactors. The invention also provides a medical device which hasincreased biocompatibility over prior art devices, and decreases orinhibits tissue-based excessive intimal hyperplasia and restenosis bydecreasing or inhibiting smooth muscle cell migration, smooth musclecell differentiation, and collagen deposition along the inner luminalsurface at the site of implantation of the medical device.

In an embodiment, a method for coating a medical device comprises thesteps of: applying at least one layer of a biocompatible matrix to thesurface of the medical device, wherein the biocompatible matrixcomprises at least one component selected from the group consisting of apolyurethane, a segmented polyurethane-urea/heparin, a poly-L-lacticacid, a cellulose ester, a polyethylene glycol, a polyvinyl acetate, adextran, gelatin, collagen, elastin, tropoelastin, laminin, fibronectin,vitronectin, heparin, fibrin, cellulose and carbon and fullerene, andapplying to the biocompatible matrix, simultaneously or sequentially, atherapeutically effective amounts of at least one type of antibody,antibody fragment or a combination thereof, and at least one compoundwhich stimulates endothelial cell growth and differentiation.

A bioabsorbable, biocompatible, and biodegradable scaffold may beoperatively configured to afford deliverability, flexibility, and radialstretchability very suitable for implantation in the pulsatilemovements, contractions and relaxations of, for example, thecardiovascular system.

For example, the medical device could comprise a polymer with low immunerejection properties such as a bioabsorbable polymer composition orblend, having a combination of mechanical properties balancingelasticity, rigidity and flexibility. The polymer composition couldproduce a low antigenicity by means of a biocompatible base material,such as, without limitation, a bioabsorbable polymer, copolymer, orterpolymer, and a copolymer or terpolymer additive. These kinds ofpolymer structures may advantageously undergo enzymatic degradation andabsorption within the body. In particular, the novel composition mayallow for a “soft” breakdown mechanism that is so gradual that thebreakdown products or polymer components are less injurious to thesurrounding tissue and thus reduce restenotic reactions or inhibitrestenosis entirely.

The present inventors have also proposed novel designs which may employsuch bioabsorbable, biocompatible and biodegradable material to makeadvantageous scaffolds, which may afford a flexibility andstretchability very suitable for implantation in the pulsatilemovements, contractions and relaxations of, for example, thecardiovascular system.

Embodiments disclosed herein include, medical devices such as stents,deformable vascular devices, synthetic grafts and catheters, which mayor may not comprise a bioabsorbable polymer composition for implantationinto a patient.

In one embodiment, a cardiovascular tube-shaped expandable scaffold suchas a stent is provided, having a low rejection or immunogenic effectafter implantation, which is fabricated from a bioabsorbable polymercomposition or blend having a combination of mechanical propertiesbalancing vascular scaffolding, elasticity, rigidity and flexibility,which properties allow bending and crimping of the scaffold tube onto anexpandable delivery system for vascular implantation. The instantdevices can be used in the treatment of, for example, vascular diseasesuch as atherosclerosis, restenosis, and vascular remodeling provided asboth a crimped and expanded structure, which can be used in conjunctionwith balloon angioplasty.

In an embodiment, the medical device can be provided as an expandablescaffold, comprising a plurality of meandering strut elements orstructures forming a consistent pattern, such as ring-like structuresalong the circumference of the device in repeat patterns (e.g., withrespect to a stent, without limitation, throughout the structure, at theopen ends only, or a combination thereof). The meandering strutstructures can be positioned adjacent to one another and/or inoppositional direction allowing them to expand radically and uniformlythroughout the length of the expandable scaffold along a longitudinalaxis of the device. In one embodiment, the expandable scaffold cancomprise specific patterns such as a lattice structure, dual-helixstructures with uniform scaffolding with optional side branching.

An embodiment provides an expandable biodegradable tubular scaffoldwhich includes a plurality of biodegradable first meanders forming aninterconnected mesh, wherein the mesh extends circumferentially about alongitudinal axis; wherein each of the biodegradable first meanders aremanufactured from a polymer which crystallizes under the strain ofexpansion of said tubular scaffold, and a plurality of biodegradablesecond meanders, each of said second meanders being separate fromanother, and each extending circumferentially about said longitudinalaxis in a single orthogonal plane. The second meanders nest in, andinterconnect to, the first meanders, and have at least two closed loopconnectors intervening between segments of each second meanders, whichconnectors are capable of deformation and crystallization under fullexpansion during intravascular implantation of said tubular scaffold.This extra expansion range serves to prevent overstretching the secondmeanders or hoops and thereby necking or structural integrity of thesecond meanders or hoops.

In one embodiment, a bioabsorbable and flexible scaffold circumferentialabout a longitudinal axis so as to form a tube, the tube having aproximal open end and a distal open end, and being expandable from anunexpanded structure to an expanded form, and being crimpable, thescaffold having a patterned shape in expanded form comprising:

a plurality of first meandering strut patterns, each of the firstmeandering strut pattern being interconnected to one another to form aninterconnected mesh pattern circumferential about the longitudinal axis;

at least two second strut patterns nested within the interconnected meshpattern, each of said second strut patterns comprising a hoopcircumferential about the longitudinal axis, said hoop having an innersurface proximal to the longitudinal axis and an outer

surface distal to the longitudinal axis, the hoop inner and outersurfaces about their circumferences being orthogonal to the longitudinalaxis and within substantially the same plane; and

at least two expansion loops intervening in the second meanders so asprovide extra hoop length when stretched to the crystallized limit atwhich the second meanders would neck and fail.

In one embodiment, the first meandering strut patterns can be generallyparallel to said longitudinal axis, generally diagonal to saidlongitudinal axis, generally orthogonal to said longitudinal axis, orgenerally concentric about said longitudinal axis. The second strutpatterns can be made of a material which substantially crystallizes whensaid tube is in its expanded state, but does not substantiallycrystallize in its unexpanded state. The second strut patterns caninclude at least one hoop having a through-void, wherein said at leastone hoop is configured to permit its radius to be expanded when said atleast one hoop is subject to an expanding force which exceeds itsnominal expanded state, but a force that does not result in hoopfailure.

In one embodiment, each of the first meandering strut patterns of thescaffold is essentially sinusoidal, and each of the second strutpatterns is substantially non-sinusoidal. The first meandering strutpatterns of a scaffold can extend from the proximal open end to thedistal open end of the tube. In another embodiment, each of the secondstrut patterns can be found at the proximal open end and the distal openend. In one embodiment, each of the second strut patterns is furtherfound between the proximal open end and the distal open end.

In one embodiment, the scaffold comprises a structure wherein each ofthe second strut patterns can be found between the proximal open end andthe distal open end but not at the proximal open end or distal open end.In another embodiment, the scaffold comprises a structure wherein thesecond strut patterns can be found at least one of the proximal open endor the distal open end.

In a specific embodiment, the scaffold comprises a stent having anunexpanded configuration and an expanded configuration; an outer tubularsurface and an inner tubular surface, the stent comprising: a pluralityof biodegradable, paired, separate circumferential bands having apattern of distinct undulations in an unexpanded configuration andsubstantially no undulations in an expanded configuration, theundulations of the biodegradable, paired, separate circumferential bandsin the stent in an unexpanded state being incorporated into asubstantially planar ring in an expanded state, and a plurality ofbiodegradable interconnection structures spanning between each pair ofcircumferential bands and connected to multiple points on each band ofthe paired bands.

In an embodiment, the stent interconnecting structures comprise apattern of undulations both in an unexpanded and expanded configuration.In an alternate embodiment, the interconnection structures comprise apattern containing no undulations in both an unexpanded and expandedconfiguration. The interconnection structures of the stent can expandbetween undulations of paired circumferential bands.

In another embodiment, a biosorbable and flexible scaffoldcircumferential about a longitudinal axis and substantially forming atube, the tube having a proximal open end and a distal open end, andbeing crimpable and expandable, and comprising in expanded form: a) atleast two rings circumferential about the longitudinal axis, the ringshaving an inner surface proximal to the longitudinal axis, an outersurface distal to the longitudinal axis, a top surface proximal to theproximal open end and a bottom surface proximal to the distal open end,the ring inner and outer surfaces about their circumferences beingorthogonal to the longitudinal axis and within substantially the sameplane, and b) a plurality of meandering strut patterns located betweenthe at least two rings and circumferential coursing about thelongitudinal axis; the plurality of meandering strut patterns connectedto the rings at least two connection points on the circumference of eachring, and each connection point on the circumference of the ring on boththe top ring surface and the bottom ring surface; wherein each of theconnection points with any particular ring is symmetrical in structureabove and below the upper and lower surface of the ring.

In one embodiment, the scaffold comprises a structure wherein theconnection points of the rings, the meandering strut patterns above thering upper surface and below the ring lower surface in conjunction forma stylized, letter H configuration. In another embodiment, the scaffoldcan comprise a structure wherein at the connection points of the rings,the meandering strut patterns above the ring upper surface and below thering lower surface in conjunction form two abutting sinusoids. In analternate embodiment, the scaffold can comprise a structure wherein atthe connection points of the rings, the meandering strut patterns abovethe ring upper surface and below the ring lower surface in conjunctionform two sinusoids with intervening structure connecting the same andthe ring. In one embodiment, the connection points of the rings havebetween 2 through 6 meandering strut pattern connections at eachconnection.

In another embodiment, an expandable biodegradable tubular scaffoldcomprising a plurality of biodegradable first meanders forming aninterconnected mesh. The mesh extending circumferentially about alongitudinal axis; wherein each of the biodegradable first meanders aremanufactured from a racemic polymer which crystallizes under the strainof expansion of the tubular scaffold, and also comprising a plurality ofbiodegradable second meanders, each of the second meanders beingseparate from another, and each extending circumferentially about thelongitudinal axis in a single plane, the second meanders being nestedin, and interconnected to, the first meanders. In this embodiment, thescaffold's first meanders are generally parallel to the longitudinalaxis, generally diagonal to the longitudinal axis, generally orthogonalto the longitudinal axis, or are concentric about the longitudinal axis.The second meanders are made from a material which crystallizes when thetube is in its expanded state, but does not substantially crystallize inits unexpanded state, and at least one of the second meanders includesat least one through-void, which is configured to permit stretching ofthe second member without failure of the member.

In one embodiment, the first meanders form a strut pattern that issinusoidal when the tube is in an expanded form, the second meandersform a strut pattern that is substantially non-sinusoidal when the tubeis in an expanded form. In this and other embodiments, the firstmeanders form a strut pattern that extends from the proximal open end tothe distal open end of the tube, and the second meanders form a strutpattern that is found at the proximal open end and the distal open end.The second meanders can also form a strut pattern that is further foundbetween the proximal open end and the distal open end, or the secondmeanders form a pattern that is found between the proximal open end andthe distal open end but not at the proximal open end or the distal openend.

In another embodiment, the stent conformation is variably adaptable toluminal diameters of the cardiovascular contours such that the secondmeander can be flexibly expanded beyond the rigidly and elasticallystretched stable hoop conformation beyond the maximal crystallizationstage, however, without causing collapse of the hoop structure. Thisadditional built-in flexible expansion is obtained by the special loopinserts along the second meander struts. More specifically, such a loopinterconnects at least two segments of the second meander strut, whereinthe loop before expansion forms an oval ring lying in a longitudinalaxis direction. When the second meander at its maximal stretch expansionto form a hoop structure has to be further expanded for a better luminalfit or hold in the vascular system in situ, the loop can be stretchedorthogonally forming an oval ring in the direction of the stretched hoopstructure.

In one embodiment, at least one of the plurality of paired biodegradablecircumferential bands includes along its outer tubular surface, aradio-opaque material capable of being detectable by radiography, MRI orspiral CT technology. Alternatively, at least one of the interconnectionstructures includes a radio-opaque material along its outer tubularsurface, which can be detectable by radiography, MRI or spiral CTtechnology. The radio-opaque material can be housed in a recess on oneof the circumferential bands, or in a recess on one of theinterconnection structures. In one embodiment, a least one of theinterconnection structures and at least one of the circumferential bandsincludes a radio-opaque material along the outer tubular surface, whichis detectable by radiography, MRI or spiral CT technology.

In an alternate embodiment, a method for fabricating a tube-shapedscaffold comprises: preparing a racemic poly-lactide mixture;fabricating a biodegradable polymer tube of the racemic poly-lactidemixture; laser cutting the tube until a desired scaffold is formed. Inone option of such embodiment, the fabrication of the scaffold can beperformed using a molding technique, which is substantiallysolvent-free, or an extrusion technique.

There is also provided a method for fabricating the tube-shaped scaffoldcomprising, blending a polymer composition comprising a crystallizablecomposition comprising a base polymer of poly L-lactide or polyD-lactide linked with modifying copolymers comprising poly L (orD)-lactide-co-tri-methylene-carbonate or poly L (orD)-lactide-co-.epsilon.-caprolactone in the form of block copolymers oras blocky random copolymers wherein the lactide chain length issufficiently long enough to allow cross-moiety crystallization; moldingthe polymer composition to structurally configure the scaffold; andcutting the scaffold to form the desired scaffold patterns. In thisembodiment, the blended composition may comprise a racemic mixture ofpoly L-lactide and poly-D lactide. Accordingly, medical devices such asa stent, produced by this method may consist essentially of a racemicmixture of a poly-L and poly-D lactide. In this embodiment, the stentcan comprise other polymer materials such as trimethylcarbonate. In oneoptional composition of such embodiment wherein the device comprisestrimethylcarbonate, the amount of trimethylcarbonate does not exceedmore than 40% of the weight of the stent.

In another embodiment, an expandable tube-shaped scaffold having aproximal end and a distal end defined about longitudinal axis isprovided. The scaffold comprises: (a) a plurality of first meanderingstrut elements interconnected with one another at least one point insuch a manner to form a circumferential tube-shaped structure, the firstmeandering strut elements forming a tubular mesh which is crimpable andexpandable; (b) a second meandering strut element which is operativelyconfigured to be crimpable and expandable and configured to form ahoop-shaped strut of the scaffold after expansion; and (c) a lockingmeans permitting the scaffold to the locked in a crimped position;wherein the scaffold comprises a expansion crystallizable, bioabsorbableracemate polymer composition or blend.

In one lock embodiment, the tube-shaped scaffold can comprise astructure wherein the locking means is a two-part portion of one ordifferent meandering strut elements located at or near both the proximaland distal ends of the tube-shaped scaffold. In this embodiment, thetwo-part portion of the locking means can entail, for example, asnap-fit engagement in the crimped position of the scaffold, wherein thelocking means is disengaged by scaffold expansion. In alternateembodiments, the tube-shaped scaffold can comprise a locking meanscomprising a snap-fit key-in-lock configuration wherein the designresembles a dovetail type interlocking means. The tube-shaped scaffoldcan also comprise locking means comprising a snap-fit key-in-lockconfiguration resembling a ball-joint type interlocking means; acantilever arm hooking an oppositely shaped end piece of the plasticscaffold, and the like.

The tube-shaped scaffold can be mounted or carried on a expandableballoon carrier device and can be sized to stretch from a crimped tubediameter to a diameter sufficient for implantation inside the lumen of avascular system.

In another embodiment, the expandable scaffold comprises a set ofinterlocking meandering struts stabilizing the implanted scaffold in anexpanded or implanted configuration, wherein the scaffold polymerundergoes a molecular reorientation and crystallization during theradial strain of expansion. The scaffold can vary from a cylindrical toa conal shape or combination thereof. In the embodiments describedherein, the scaffold's biodegradable polymer displays breakdown kineticssufficiently slow to avoid tissue overload or other inflammatoryreactions. The polymer core material comprising at least oneencapsulated drug for localized treatment of the vascular wall andlumen.

In certain embodiments, novel stent designs with coatings are providedwhich are bioabsorbable, biocompatible, and biodegradable. Scaffoldsmade from such material may afford deliverability, flexibility, andradial stretchability very suitable for implantation in the pulsatilemovements, contractions and relaxations of, for example, thecardiovascular system. After a period of implantation, the stent maybegin to degrade once normal endothelium has been established by thepresence of the coating.

For example, the medical device could comprise a polymer with low immunerejection properties such as a bioabsorbable polymer composition orblend, having a combination of mechanical properties balancingelasticity, rigidity and flexibility. The polymer composition couldproduce a low antigenicity by means of a biocompatible base material,such as, without limitation, a bioabsorbable polymer, copolymer, orterpolymer, and a copolymer or terpolymer additive. These kinds ofpolymer structures may advantageously undergo enzymatic degradation andabsorption within the body. In particular, the novel composition mayallow for a “soft” breakdown mechanism that is so gradual that thebreakdown products or polymer components are less injurious to thesurrounding tissue and thus reduce restenotic reactions or inhibitrestenosis entirely.

In certain embodiments, there are provided polymeric designs, withcoatings which may employ bioabsorbable, biocompatible and biodegradablematerial to make advantageous scaffolds, which may afford flexibilityand stretchability very suitable for implantation in the pulsatilemovements, contractions and relaxations of, for example, thecardiovascular system. In these embodiments, the coatings can be appliedprior to or cutting or making the designs. The coatings can be appliedin various manners, and can vary in content depending on the site ofapplication on the device. For example, a coating on a luminal surfaceof the medical device can comprise ligands for recognizing and bindingendothelial cells to form an endothelium, and can also comprise one ormore pharmaceutical substances for inducing differentiation ofendothelial cells and/or maintaining the endothelial cells function. Inthis and other embodiments, the abluminal coating can comprise one ormore pharmaceutical substances for example, that inhibit restenosis orprevent thrombus formation.

The coating can comprise one or more layers of a matrix and at least onetype of ligand such as antibodies, antibody fragments or combinations orantibodies and antibody fragments; peptides and small molecules whichbind and capture endothelial cells in vivo at the site of implantationof the device. The coating can further comprise a pharmaceuticalsubstance for delivery to target tissue. In this embodiment,pharmaceutical substances, for example, for reducing restenosis, inhibitsmooth muscle cell migration, induce nitric oxide synthetase, can beused in conjuction with the coating. The pharmaceutical substances canbe applied in various manner such as in layers.

FIG. 1 is a photograph of a bioabsorbable medical device of theinvention consisting of a stent design mounted along its longitudinalaxis on a catheter. In this embodiment, the stent is coated with matrixlayer comprising a bioabsorbable polymer and a ligand consisting ofantibodies against CD34 positive cells.

The figures provided herewith depict embodiments that are described asillustrative examples that are not deemed in any way as limiting thepresent invention.

EXAMPLE 1

Bioabsorbable polymer tubes for use to make an embodiment of theinvention were made from polymer compositions as described above.Uncoated tubes and tubes that had been coated as described above,comprising a coating with Anti-CD34 antibodies coated on a polymermatrix were analyzed for the ability to bind antibodies on theirsurface. Prior to testing the tubes for cell binding, tubes that werecoated with a layer of antibodies were examined for the amount ofantibody binding on their surface. The experiments were repeated threetimes. The results of these studies are shown in FIG. 2.

As seen in FIG. 2, the untreated tube, plasma treated with an oxygenplasma followed by an argon plasma tubes, and tubes coated with a matrixdid not contain any anti-CD34 antibodies per tube in any of the trialsperformed. In contrast polymer tube were coated with a coating solutioncomprising a bioabsorbable polymer, followed by a buffered solutioncontaining anti-CD34 antibodies had approximately 600 to 800 ng ofantibodies (per tube) attached to their surface. The tubes were thentested for cell binding activity in in vitro experiments using Kg1a,CD34 positive cells. Only those tubes processed to be coated withsolutions containing anti-CD34 were found to contain bound antibody ontheir surface.

EXAMPLE 2

The uncoated and coated tubes and tubes that were plasma treated wereincubated with Kg1a cells. After incubation, the tubes were rinsed inbuffered saline to remove unbound cells and the tubes were fixed andprocess to identify cells bound to the devices. Cell binding to thetubes was determined by staining the tubes tested after incubation witha fluorescent, nuclear,DAPI((4′,6-diamidino-2-phenylindole)dihydrochloride) staining procedureand examined under a fluorescent microscope. The results of theseexperiments are shown in FIGS. 3 through 6.

FIG. 3 shows a representative bioabsorbable tube with a coatingcomprising a polymer and anti-CD34 antibodies which depicts numerousKg1a cells attached to the tube as seen by the fluorescence emitted fromthe cells. FIG. 4 is a representative uncoated tube from the experimentsand shows that the uncoated tubes had very few cells attached thereon.It appeared that the majority of the signal from these groups was due tobackground fluorescence. FIG. 5 is a representative of the plasmatreated tubes which shows that binding of cells also occurred in tubes,but the binding was confined to one end of the tube. The data for theseexperiments is summarized in FIG. 6. FIG. 6 is a table showing thathaving a matrix and antibody coating on the bioabsorbable deviceenhances the binding of cells to device. Similar experiments werecarried out using bioabsorbable stents made by the present methods. Anexemplary bioabsorbable stent with a coating comprising a polymer andanti-CD34 antibodies which was exposed to Kg1a cells as discussed aboveshows that Kg1a bound to its surface as seen in FIG. 7.

One embodiment of the invention is illustrated in FIG. 8, wherein thebioabsorbable medical device is a tubular structure comprising a body 5having a lumen or a conduit 10. In this embodiment, there is provided aninner coating, comprising one or more layers, as shown in FIG. 8 as twolayers 15 and 20, and an outer coating, which may comprise one or morelayers, as shown in FIG. 8 as two layers 25, 30 on the surface of themedical device. For example, the inner coating may comprise at least twolayers 15, 20 of a material which for example, can comprise an antibodylayer 15 and a pharmaceutical composition 20 with or without a matrix.Multiple arrangement of layers can be deposited on either surface of thedevice and may contain different components or pharmaceutical substancesor the layers can be the same. The outer coating 25, 30 surrounding thedevice structure can be the same or different in composition and canalso comprise one or more pharmaceutical substance or compositiondepending on the need of the patient. In this embodiment, the device isdepicted with multiple layers.

FIG. 9 is an illustration of a stent with a coating showing aperspective view of a stent strut 55 with the layer in the outer surfaceand the inner with a coating with the outermost layer 45 depicting anantibody containing layer, an abluminal layer 50 comprising abiodegradable polymer with a drug load for release into the vessel wall,and the luminal coating 60 comprising a drug composition for releaseinto the vessel surface after implantation. Spaces between the stentstruts 40 are also depicted.

While the invention has been particularly shown and described withreference to particular embodiments, it will be appreciated thatvariations of the above-disclosed and other features and functions, oralternatives thereof, may be desirably combined into many otherdifferent systems or applications. Also that various presentlyunforeseen or unanticipated alternatives, modifications, variations orimprovements therein may be subsequently made by those skilled in theart which are also intended to be encompassed by the following claims.

What is claimed is:
 1. An expandable stent, comprising bioabsorbablepolymer scaffold and a coating, wherein the expandable stent comprises aplurality of first meandering strut patterns forming an interconnectedmesh, and at least one second strut pattern comprising a hoopcircumferential about the longitudinal axis of the expandable stent,wherein the second strut pattern crystallizes when the stent isexpanded, the bioabsorbable polymer scaffold comprising, at least about70% (w/w) of a base polymer comprising a poly (L-lactide) moiety, and/ora poly (D-lactide) moiety, and/or poly L-lactide-co-PEG moiety, and/orpoly D-lactide-co PEG moiety, linked with a modifying polymer comprisingpoly (L-lactide-co-Tri-methylene-carbonate) or poly(D-lactide-co-tri-methylene-carbonate) or poly(L-lactide-co-ε-caprolactone) or poly (D-lactide-co-ε-caprolactone),wherein the coating comprises a ligand specific to an progenitorendothelial cell surface antigen selected from the group consisting ofCD34 CD45, CD133, CD14, CDw90, CD117, HLA-DR, VEGFR-1, VEGFR-2, CD146,CD130, CD131, stem cell antigen, stem cell factor 1, Tie-2, MCH-H-2Kkand MCH-HLA-DR.
 2. The expandable stent of claim 1, wherein the secondstrut pattern further comprises a through-void.
 3. The expandable stentof claim 1, wherein the ligand is configured to bind target cells invivo.
 4. The expandable stent of claim 1, wherein the coating furthercomprises a bioabsorbable matrix.
 5. The expandable stent of claim 4,wherein the bioabsorbable matrix comprises at least one of the groupconsisting of: dextran, tropoelastin, elastin, laminin, fibronectin,fibrin, collagen, basement membrane proteins, and cross-linkedtropoelastin.
 6. The expandable stent of claim 1, further comprising apharmacological substance.
 7. The expandable stent of claim 6, whereinthe pharmacological substance is at least one of the group consistingof: cyclosporin A, mycophenolic acid, mycophenolate mofetil acid,rapamycin, rapamycin derivatives, biolimus A9, CCI-779, RAD 001,AP23573, azathioprene, pimecrolimus, tacrolimus (FK506), tranilast,dexamethasone, corticosteroid, everolimus, retinoic acid, vitamin E,rosglitazone, simvastatins, fluvastatin, estrogen, 17β-estradiol,hydrocortisone, acetaminophen, ibuprofen, naproxen, fluticasone,clobetasol, adalimumab, sulindac, dihydroepiandrosterone, testosterone,puerarin, platelet factor 4, basic fibroblast growth factor,fibronectin, butyric acid, butyric acid derivatives, paclitaxel,paclitaxel derivatives, LBM-642, deforolimus, and probucol.
 8. Theexpandable stent of claim 6, wherein the stent is a drug-eluting stent.